In general, an archive device has been used for storing digital content such as music, movies, electronic mails, medical images, and document data in an integrated manner for a long period of time. The archive device is connected to a plurality of external devices through a network, stores various digital content (hereinafter referred to as “data”) received from the external devices, and transmits the stored data to the external devices in accordance with reference requests externally supplied.
Specifically, the archive device includes a plurality of storage devices (such as a disk array and a tape library) and a processor which performs a writing process to the storage devices and a reading process from the storage devices. The processor writes data supplied from the external devices to the storage devices. At this time, the processor generates metadata (such as a reception date, a transmission source, and a storage place) for the received data and stores the metadata. Then, the processor refers to the metadata in accordance with a reference request issued by a user, reads data corresponding to the metadata from one of the storage devices, and transmits the data to one of the external devices.
Note that the archive device has a single instance function of preventing storage of the same data so that data which has been stored is not stored again. Specifically, the archive device stores property information which is obtained by associating a hash value calculated from data which has been stored and a data capacity of the data for each data. Then, the archive device calculates a hash value of data which is newly requested to be stored, and determines whether the same data has been stored by comparing the calculated hash value and a data capacity of the data which is requested to be newly stored with the property information stored therein.
For example, when newly receiving data having a hash value and a data capacity which are the same as those stored as property information of the archive device, the archive device does not store the data but generates metadata of the data and stores the metadata associated with the property information.
Furthermore, in recent years, an archive device which allows a recording medium which stores data to be removed as a portable recording medium so that load applied to a network at a time of data transmission and load applied to the archive device when data is copied are reduced has been known (refer to Japanese Laid-open Patent Publication No. 09-330263).
In the related art described above, there arises a problem in that a process of storing data is not smoothly performed. Specifically, in the related art described above, the archive device calculates a hash value when data is to be stored, and therefore, in a case where a plurality of external devices request storage of data, for example, load applied to a CPU of the archive device is increased, and accordingly, the process of storing data is not smoothly performed.
Furthermore, in the related art described above, in a case where it is determined that data requested to be stored using the single instance function has been already stored, transmitted data is discarded. Therefore, the load applied to the network is increased owing to an unnecessary data transmission.